Track-tamping assembly

ABSTRACT

A track-tamping assembly including a pair of opposed, vibratory and reciprocable tamping tools is mounted with at least some of the mounting and/or drive means for the tamping tools enclosed in a common housing which forms part of a common lubricating system for all points of the assembly requiring lubrication.

United Stat's Patent 721 inventors Franz Plasser 50 Field of Search 1 v104/12, 10, Johnannesgase 3, 1010 Vienna; l 1 Jose! Them-er,Johnannesgase 3, i010 1 Vienna, both of, Austria References Cited {21 1Appl. No. 819,665 UNITED STATES PATENTS Filed 2911969 3 357 366 12 1967PI 1 1 10412 451 Patented June 29, 1971 asset e a [32] Priority Apr. 29,1968 Primary ExammerArthur L. La Point [33] Austria AssistantExaminer-Richard A. Bertsch [31] A 4172/68 Anorney-Kurt Kelman y I I I[54] TRACKJAMPING ASSEMBLY ABSTRACT: A track-tampmg assembly ncluding apair of n a 9 Drawi'n Fi ppposed, vibratory and rec1procab1e tamplngtools 1s mounted t g with at least some of the mounting and/or drivemeans for the [52] (1.8. CI 104/12 tamping tools enclosed in a commonhousing which forms part E0lb 27/16, of a common lubricating system forall points of the assembly E0 1 in 27/20 requiring lubrication.

VII

PATENTEUJUNZQIB?! I 3589297 SHEETIUFZ fWEl IN VliN'l ()AJ Jore? THEvneRMevr SHEET 2 OF 2 PATENTED JUN29 191:

TRACK-TAMPING AISSEMBLY The present invention relates to a machine fortamping ballast underneath a track including rails supported on aplurality of ties resting on the ballast and spaced in the direction oftrack elongation, and more particularly to improvements in thelubrication of the moving parts of track-tamping assemblies mounted onsuch machines. Machines of this type include means for movably mountingthe tamping tools and drive means for pivoting, vibrating and verticallymoving the tamping tools.

This invention is useful in connection with the known type of tracktamping assemblies which include a pair of opposed tamping tools andmeans mounted on a vertically adjustably mounted tamping tool carrierfor vibrating and reciprocating the opposed tamping tools in thedirection of track elongation. Each tool has two ends, and the lower endis arranged for immersion in the ballast adjacent one of the ties, withthe one tie positioned between the opposed tools of the pair. Theinvention is very advantageously applied to the known type of twin tracktamping assemblies which include two such pairs of opposed tampingtools, the pairs of tools being so spaced from each other in thedirection of track elongation that the tools of each pair which areadjacent to each other are at a smaller distance from each other thanthe distance between adjacent ties whereby the adjacent tools of the twopairs of tools may be duit to the pump which delivers the oil to theconditioning device for reuse.

In a preferred embodiment, the housing defining the lubricating mediumsump constitutes the vertically adjustable carrier for the track-tampingassembly. This housing may enclose only the pivotal mountings of thetamping tools immersed in the sump, or it may enclose all moving partsof the assembly. While the pivotal mountings for the tamping toolsimmersed in the ballast between two adjacent ties. With either type oftrack tamping assembly, a common vibrating means may be provided for alltamping tools, as shown, for instance, in our U.S. Pats. Nos. 3,357,366and 3,429,276.

These known assemblies form a unit, at least to a certain ex tent,because the drives for the tools are coordinated. Also, a series oftransversely arranged tools is associated with each rail, and all theassociated tools move with one pair which is driven. Therefore, theinvention is described only in connection with the one, driven pair inany series of pairs of tools which are transversely aligned.

While these known track-tamping assemblies have advanced far in thedirection of compact construction, it is the primary object of thepresent invention further to advance in this direction and to unite allparts of the track-tamping as sembly into one well lubricated unitrequiring a minimum of space.

This and other objects are accomplished in accordance with thisinvention by providing a common lubricating system which includes ahousing defining a common sump for lubricating medium for the tampingtools. The housing encloses at least some, and preferably all, themounting and/or drive means for the tamping tools.

Such a common lubricating system very effectively contributes to arational mounting and combination of all moving parts of thetrack-tamping assembly, and to provide an effective tamping unit. It isquite useful with a variety of tamping tool assembly types.

In one preferred embodiment, a twin track-tamping assembly for eachtrack rail is mounted in a common housing and the two housings aresupplied from a common lubricating medium source. However, it is alsopossible to mount two separate single or twin-track tamping assembliesspaced in the direction of track elongation on a track tamper, suchassemblies being movable in relation to each other and each assemblybeing enclosed in a common housing, and all housings beingsupplied from a common lubricating medium source.

The common lubricating system may include a common source of lubricatingmedium and a circulating system including a pump, an oil-conditioningdevice including an oil filter and/or cooling system, a conduit fordelivering the reconditioned oil from the device to the housings of thetrack-tamping assemblies and/or to all the lubricating points thereof, asump in the housings whence the used oil is returned through a conareimmersed in the oil sump, a centrally supplied oil conduit systemdelivers oil to other points of the assembly which require lubrication,such conduits including, if desired, oil spray nozzles, baffles andother oil-distributing devices properly guiding the oil to thelubrication points. DETAILED DESCRIPTION OF DRAWING The above and otherobjects, advantages and features of the present invention will becomemore apparent from the following detailed description of some preferred,embodiments, taken in conjunction with the accompanying drawing whereinFIGS. 1 to 3 are schematic side views of three different types ofgenerally conventional ballast tamping and trackleveling machineswherein this invention may be used to advantage;

FIG. 4 is a vertical section along line IV-IV of FIG. 7 of a mounting ofa twin-tamping tool assembly according to one embodiment of theinvention;

FIG. 5 and 6 are schematic views showing two additional embodiments oftamping tool mountings according to the invention;

FIG. 7 is an enlarged end view'of a pair of transversely aligned tampingtool assemblies, taken in the direction of arrow VII of FIG. 4; and

FIGS. 8 and 9 are schematic top views illustrating the positions of thetamping tool assemblies in the machines of FIGS. 2 and 3, respectively.

DETAILED DESCRIPTION To avoid redundancy, like parts operating in a likemanner have been designated by the same reference numerals in FIGS. 1 to3. Track-tamping and leveling machines of such general types are wellknown and are described, for instance, in our U.S. Pats. Nos. 3,192,870,3,2l1,l09,'3,357,366 and application Ser. No. 668,266, filed July 25,1967. now U.S. Pat. No. 3,494,297. They include a carriage frame 1having front and rear wheels 2, 2 mounted for movement on track 3 whoserails are supported on a plurality of ties 4i resting on the ballast(not shown) and spaced in the direction of track elongation. Referringmore specifically to FIG. 1, a carrier 5 is vertically adjustablymounted on the carriage frame and a tracktamping assembly comprising apair of opposed tamping tools 6 is mounted on the carrier for verticalmovement therewith. The tamping tools are vibratory and reciprocable inthe direction of track elongation.

As indicated in FIGS. 1 to 3, present-day track tampers also includemeans for grading or leveling the track, including a track-lifting means9 at the front end of the overhanging portion of the carriage frame, anda reference system in respect of which the track is leveled, this systemincluding a reference line 10 extending from a front bogiie 11 in theuncorrected track section to a rear station 12 resting on thecorrectedtrack section. The reference system also includes a stop 13 (and I3 inFIG. 3) cooperating with the reference line and resting on the tracksection being tamped by each track tamping assembly. All of thisstructure and its function are well known.

As is conventional, a separate tamping tool assembly, each consisting ofa series of pairs of associated opposed tamping tools, is mounted on acarrier vertically above each rail, of the track. According to thepresent invention, a common or central lubricating medium supply' source7 is connected by a lubricating medium supply conduit system to alllubricating points of the tamping tool assemblies so that all assemblieshave a common lubricating system although each assembly is enclosed in ahousing defining a common sump for the lubricating medium for eachassembly.

In the embodiment of FIG. 2, each tamping tool assembly includes aseries of two pairs of opposed tamping tools, and the pairs of tools areso spaced from each other in the direction of track elongation that thetools of each pair which are adjacent to each other are at smallerdistance from each other than the distance between adjacent ties wherebythe adjacent tools of the two pairs may be immersed in the ballastbetween the adjacent ties.

If each assembly associated with a respective track rail is housed in aseparate carrier 5', the two housings are again connected to the samelubricating medium supply 7 (see also FIG. 8). However, it is alsopossible to mount the assemblies for both rails in a single housing.

In the track tamping and leveling machine of FIG. 3, two twin units 5'are mounted for movement in relation to each other along the directionof track elongation. In this embodiment, the carriage frame 1' is ofbridgelike configuration and runs on swivel trucks 2', 2' supporting arespective end of the carriage frame. A support frame 14 for the tampingtool assemblies is supported on the carriage frame intermediate its endsand has guide rails on which the tamping tool assembly carriers aremounted for movement in the direction of track elongation. Thetrack-lifting means 9 is mounted at the front end of the support frameand, if laterally movable, may also serve for track lining. A hydraulicjack engages the track rails between the two twin track tampingassemblies in the center of the support frame 14 and, if the machinealso serves as a track liner, this jack may be laterally movable toserve for lining the track at this point. However, jack 15 servesprimarily to press downwardly against the track and thus to preventunwanted upward movement of the track at this point and thus to maintainthe track in the graded position. As will appear from the top view ofFIG. 9, four separately housed twin track tamping assemblies of thistype may still be centrally supplied from a common lubricating mediumsource 7.

A preferred mounting for a twin-tamping tool assembly is shown in FIG.4. In this embodiment, the tamping tool assembly carrier is constitutedby a common housing 16 defining a sump for a lubricating medium, such asoil. The housing 16 is vertically adjustably mounted on columns 17, 17in the carriage frame 1 or 1' for moving the lower ends of the tampingtools into and out of immersion in the ballast.

Each tamping tool of the twin tamping tool assembly is shown to includea pivot 19 intermediate its ends about which the tool is reciprocated inthe direction of the track elongation, the tool being a lever swingingabout this pivotal mounting. An upper portion 21 of the tamping toolsextends from pivotal mounting 19 into housing 16 and a lower portion 18'extends downwardly from the pivotal mounting and outwardly of thehousing. The lower portion 18' of the tamping tools constitutes a mountfor tamping tool jaw 18.

The housing 16 has a bottom formed with concave portions accommodatingrespective pivots 19 of the tamping tools which are flooded withlubricating oil. Suitable sealing means constituted by gaskets 19' areprovided around the tamping tool pivots for preventing leakage of oilthrough the housing bottom. The upper and lower tamping tool portionsare detachably connected by means of a bolt 22 extending transversely tothe axis of the tool, as best seen in FIG. 7, a sealing gasket 23 beinginterposed between the forked upper end of the lower tamping toolportion 18' and the lower end of the upper tamping tool portion 21fitting into the forked upper end of the lower tool portion. In thisclamping arrangement, the relative angle of the tamping tool portions inrespect of each other may be readily adjusted while the gasket 23remains in place so that the distance between the lower ends of thetools of each pair may be changed, for instance to tamp double ties.

As is best seen in FIG. 7, each housing 16 consists of detachablyconnected wall portions 16, 16", which may be bolted together alongtheir mating flanges so that the housing may be opened for access to theparts mounted therein, the shafts or pivotal mountings for the movingparts in the housing being supported in the housing wall. Thesubdivision of the Y in the illustrated embodiment.

housing into two or more wall portions thus makes it possible readily toreplace individual parts in the housing by removing one of the wallportions temporarily.

In the illustrated embodiment of the housing, the housing for thetrack-tamping assembly associated with a respective one of the trackrails comprises a center portion 16" and two lateral portions 16', 16'detachably fastened to the center portion along flanges extending invertical planes parallel to the direction of track elongation so thatthe lateral wall portions may be selectively removed for access to theinterior of the housing. Suitable sealing means or gaskets extendbetween the flanges of the housing portions so that the wall of thehousing will be sealed against oil leakage in the assembled condition.FIG. 7 also shows the pulley and belt drive 38 for driving cam shaft 24which serves as a common tamping tool vibrating means for all thetamping tools.

The cam shaft is journaled in the housing wall and extends in a planewhich is transverse and vertical to the track, and runs centrallybetween columns 17, 17 on which the housing and tamping tool carrier ismounted for vertical movement. A pair of arms 25, 25 extend oppositelyfrom the cam shaft in the direction of track elongation, and the armsare vibrated by the shaft upon rotation thereof by drive 38. The upperends of the tamping tools of each. pair are linked to a respective camshaft arm in the manner now to be as is it being noted that in theillustrated embodiment, and as is conventional, a series of four as isof tamping tools are associated with each rail for tamping each tie onboth sides of the rail.

Separate drives 26 and 27 are connected to the upper ends of eachtamping tool of a pair (the three associated pairs being mounted on thesame shafts and, therefore, being driven therewith). The drivesreciprocate the opposed tamping tools in the direction of trackelongation, the illustrated drives being hydraulic motors. Atransmission element 28 is mounted in the housing 16, which holds allthe shafts and pivotal mountings of the track-tamping assembly, thefulcrum 29 of the transmission element being mounted on the housing wallindependently of the camshaft. The upper ends of the tamping tools ofeach pair are linked to a respective transmission element 28 by means ofinterposed drives 26, 27;, and each transmission element is at leastindirectly connected to the vibrating means, being linked to the outerends of the camshaft arms As shown, the transmission element isadvantageously a lever having two arms, a bell crank lever beingillustrated in FIG. 4. The upper end of one of the tamping tools of eachpair is linked to one lever arm via hydraulic motor 26, and the upperend of the other tamping tool of the pair is linked to the lever arm viahydraulic motor 27. In this manner, each pair of opposed tamping toolsis associated with one common transmission element, the structure beingidentically duplicated for each pair of the twin-tamping tool assembly(the three associated pairs moving in unison with the driven pair).

The two arms of the transmission lever 28 extend at an angle to eachother, which angle faces the vertical plane wherein the camshaft axisextends, and the upper transmission lever arm is connected to theassociated vibrating arm 25. The fulcrum 29 of the transmission lever ispositioned below a horizontal plane defined by the camshaft axis in theembodiment of FIG. 4. The upper end of the tamping tool farther removedfrom the camshaft is linked to the arm of the transmission leverextending upwardly from fulcrum 29, and the upper end of the tampingtool closer to camshaft 24 is to the arm of the transmission leverextending downwardly from fulcrum 29. In this manner, the tamping toolsof each pair are vibrated in opposite directions.

The length of the reciprocating stroke of the opposed tamping tools ofeach pair may be further varied by providing adjustable stops 30 for thereciprocating movement of the outer tool of each pair. For this purpose,a fixed stop may be mounted on the cylinder of hydraulic motor 26 and amovable stop 30 for selective engagement therewith may be mounted so asto be movable into the path of the cylinder movement by a hydraulicmotor or like drive 31. The movable stop 30 will engage the fixed stopand thus limit further movement when the stop 30 is swung into the pathof the cylinder movement of hydraulic motor 26 by drive 31. As mentionedbefore, the distance between the opposed tools of each pair is furtheradjustable by changing the angle between the upper and lower portions ofthe tools.

In the schematically illustrated embodiment of FIG. 5, like partsfunctioning in a like manner are designated by vlike reference numerals.In this embodiment, the housing 16 encloses only a part of the tampingtool assembly, i.e. only the pivots 19 of the tamping tools are immersedin a lubricating medium sump in the housing. The lubricating points ofthe other pivotal mountings and drives for the tamping tools 6 aresupplied from a common or central supply of lubricating medium 7 by alubricating medium conduit system 32.

In this embodiment, the kinematic system for connecting the uppertamping tool ends to the camshaft arms 25 also differs from that of FIG.4, the transmission element 28' being a straight two-armed lever one ofwhose arms is connected to the camshaft arm at the same point as thedrive 26' while the other transmission lever arm is connected to drive27' of the opposing tamping tool.

In the embodiment of FIG. 6, the linkage system of FIG. Sis combinedwith the housing system of FIG. 4, Le. all the pivotal mountings,shafts, etc. of the tamping tool assembly are fully enclosed within thehousing. Furthermore, this embodiment differs from those hereinbeforedescribed by a circulating lubricating medium system. In this system,the lubricating conduit system 34 includes a pump 33 which deliverslubricating medium to a device 35 for conditioning the medium, such asan oil filter and/or an oil-cooling system. The reconditioned oil isthen delivered into housing 16 and to the various lubricating points ofthe track-tamping assembly, and leaves the sump at the bottom of thehousing by gravity through an outlet whence the used lubricating mediumis returned into the conduit system by pump 33. In this manner, the oilmay be used for an extended period oftime without being changed.

FIG. 6 also shows some preferred delivery means for the lubricatingmedium to lubricate assembly points positioned outside the sump, such asspray nozzles 36, oil distributing baffles 37, which may simply be castribs in the housing wall, etc., all of which serve adequately to providelubrication for all moving parts of the assembly within the housing.

While such oil distributing means are of particular advantage in anenclosed housing, they may also find use in an arrangement similar tothat of FIG. where the sprayed or other distributed oil may then befurther directed into the sump in the housing therebelow whence it maybe recirculated in a similar manner as described in connection with FIG.6.

With twin track-tamping assemblies, it will be most useful to encloseall moving parts of the assemblies, including the vibrating and thereciprocating means for the tamping tools within a common housing, suchas shown in FIGS. 4 and 7. However, the present invention is also usefulwith simple track-tamping assemblies, such as indicated in FIG. 1, aswell as the multiple tampers illustrated in FIG. 3.

The kinematics of the tamping tool drives have been illustrated inconnection with various embodiments to indicate some possibilities ofcompactly assembling all parts in a common housing. Modifications andvariations of the exemplified systems will readily occur to thoseskilled in the art without departing from the spirit and scope of thepresent invention.

We claim:

l. A machine for tamping ballast underneath a track including two railssupported on a plurality of ties resting on the ballast and spaced inthe direction of track elongation, said machine comprising a pair oftrack-tamping assemblies each including two pairs of opposed movabletamping tools, each tool having two ends and one of the ends of thetamping tools being arranged for immersion in the ballast adjacent oneof the ties, with said one tie being positioned between the tools, andsaid pairs of tools being spaced from each other in the direction oftrack elongation so that the tools of each pair which are adjacent toeach other are at a smaller distance from each other than the distancebetween adjacent ones of said ties whereby said adjacent tools of thetwo pairs may be immersed in the ballast between said adjacent ties;means for movably mounting the tamping tools; and drive means forpivoting, vibrating and vertically moving the tamping tools; and themachine further comprising the improvement of a common lubricatingsystem whichincludes a pair of interconnected housings, each housingbeing associated with a respective one of the track rails, at leastpartially enclosing a respective one of the track-tamping assemblies andat least a portion of at least of said means for mounting and drivingthe tamping tools, and defining a common sump for lubricating medium forthe tamping tools; and the two housings being in transverse alignment.

2. The machine of claim 1, comprising two pairs of said housings, one ofthe pairs being spaced from the other pair of housings in the directionof track elongation and said pairs being movable in relation to eachother in said direction, a common lubricating system interconnecting allof said housrngs.

3. The machine of claim 1, wherein the common lubricating systemcomprises a central device for preparing and supplying the lubricatingmedium for said housings.

4. The machine of claim 1, wherein each housing constitutes a verticallyadjustably mounted carrier for the tamping tools, the pivotal mountingsof the tamping tools are immersed in said common sump, and a centrallysupplied lubricating medium conduit system directs the medium tolubricating points of the mounting and drive means of the tamping toolswhich are positioned above the sump.

5. The machine of claim 4, where-in each housing encloses the vibratingand drive means of the tamping tools.

6. The machine of claim 5, wherein the vibrating means is common to bothpairs of opposed tamping tools in each of said housings, a drive isconnected to each one of the other ends of the tamping tools of saidpairs for reciprocating the respective tamping tools in the direction oftrack elongation, and a transmission lever having two arms is interposedbetween the vibrating means and the drives of the opposed tools of eachpair, one of the lever arms being linked to the drives and the otherlever arm being at least indirectly connected to the common vibratingmeans for vibrating the tools of each pair in opposite directions.

7. A machine for tamping ballast underneath a track including railssupported on a plurality of ties resting on the ballast and spaced inthe direction of track elongation said machine comprising a tracktamping assembly including movable tamping tools, means for movablymounting the tamping tools, and drive means for pivoting, vibrating andvertically moving the tamping tools, and the machine further comprisingthe improvement of a common lubricating system which includes a housingdefining a common sump for lubricating medium for the tamping tools, thehousing enclosing at least a portion of at least one of the said meansfor mounting and driving the tamping tools, and consisting of detachablyinterconnected wall portions, and any shafts for tamping tool assemblyparts mounted in the housing for movement about said shafts arejournaled in said housing wall portions.

8. The machine of claim 7, wherein the housing consists of three of saidportions each extending in the direction of track elongation andseparated by vertical planes parallel to said direction, the two lateralhousing portions being detachably connected to the central housingportion.

9. A machine for tamping ballast underneath a track including railssupported on a plurality of ties resting on the ballast and spaced inthe direction of track elongation, said machine comprising a tracktamping assembly including movable tamping tools, means for movablymounting the tamping tools, and drive means for pivoting, vibrating andvertically moving the tamping tools, and the machine further comprisingthe improvement of a common lubricating system which includes a pivotalmountings of the tamping tools.

11. The machine of claim 9, wherein each tamping tool comprises an upperportion extending from the pivot into the housing and a lower portionextending downwardly from the pivotal mounting and outwardly of thehousing, the lower portion constituting a mount for a tamping tool jaw,the lower portion of the tamping tool has a forked upper end graspingthe lower end of the upper tamping tool portion, and a holy detachablyfastening the last-named ends together.

1. A machine for tamping ballast underneath a track including two railssupported on a plurality of ties resting on the ballast and spaced inthe direction of track elongation, said machine comprising a pair oftrack-tamping assemblies each including two pairs of opposed movabletamping tools, each tool having two ends and one of the ends of thetamping tools being arranged for immersion in the ballast adjacent oneof the ties, with said one tie being positioned between the tools, andsaid pairs of tools being spaced from each other in the direction oftrack elongation so that the tools of each pair which are adjacent toeach other are at a smaller distance from each other than the distancebetween adjacent ones of said ties whereby said adjacent tools of thetwo pairs may be immersed in the ballast between said adjacent ties;means for movably mounting the tamping tools; and drive means forpivoting, vibrating and vertically moving the tamping tools; and themachine further comprising the improvement of a common lubricatingsystem which includes a pair of interconnected housings, each housingbeing associated with a respective one of the track rails, at leastpartially enclosing a respective one of the track-tamping assemblies andat least a portion of at least of said means for mounting and drivingthe tamping tools, and defining a common sump for lubricating medium forthe tamping tools; and the two housings being in transverse alignment.2. The machine of claim 1, comprising two pairs of said housings, one ofthe pairs being spaced from the other pair of housings in the directionof track elongation and said pairs being movable in relation to eachother in said direction, a common lubricating system interconnecting allof said housings.
 3. The machine of claim 1, wherein the commonlubricating system comprises a central device for preparing andsupplying the lubricating medium for said housings.
 4. The machine ofclaim 1, wherein each housing constitutes a vertically adjustablymounted carrier for the tamping tools, the pivotal mountings of thetamping tools are immersed in said common sump, and a centrally suppliedlubricating medium conduit system directs the medium to lubricatingpoints of the mounting and drive means of the tamping tools which arepositioned above the sump.
 5. The machine of claim 4, wherein eachhousing encloses the vibrating and drive means of the tamping tools. 6.The machine of claim 5, wherein the vibrating means is common to bothpairs of opposed tamping tools in each of said housings, a drive isconnected to each one of the other ends of the tamping tools of saidpairs for reciprocating the respective tamping tools in the direction oftrack elongation, and a transmission lever having two arms is interposedbetween the vibrating means and the drIves of the opposed tools of eachpair, one of the lever arms being linked to the drives and the otherlever arm being at least indirectly connected to the common vibratingmeans for vibrating the tools of each pair in opposite directions.
 7. Amachine for tamping ballast underneath a track including rails supportedon a plurality of ties resting on the ballast and spaced in thedirection of track elongation said machine comprising a track tampingassembly including movable tamping tools, means for movably mounting thetamping tools, and drive means for pivoting, vibrating and verticallymoving the tamping tools, and the machine further comprising theimprovement of a common lubricating system which includes a housingdefining a common sump for lubricating medium for the tamping tools, thehousing enclosing at least a portion of at least one of the said meansfor mounting and driving the tamping tools, and consisting of detachablyinterconnected wall portions, and any shafts for tamping tool assemblyparts mounted in the housing for movement about said shafts arejournaled in said housing wall portions.
 8. The machine of claim 7,wherein the housing consists of three of said portions each extending inthe direction of track elongation and separated by vertical planesparallel to said direction, the two lateral housing portions beingdetachably connected to the central housing portion.
 9. A machine fortamping ballast underneath a track including rails supported on aplurality of ties resting on the ballast and spaced in the direction oftrack elongation, said machine comprising a track tamping assemblyincluding movable tamping tools, means for movably mounting the tampingtools, and drive means for pivoting, vibrating and vertically moving thetamping tools, and the machine further comprising the improvement of acommon lubricating system which includes a housing defining a commonsump for lubricating medium for the tamping tools, the housing enclosingat least a portion of at least one of the said means for mounting anddriving the tamping tools, and including a bottom, pivotal mountings forthe tamping tools are immersed in said common sump at the bottom of thehousing, and sealing means is provided around the pivotal mountings toprevent leakage of the lubricating medium through the bottom.
 10. Themachine of claim 9, wherein the housing bottom defines downwardlydirected concave portions housing the pivotal mountings of the tampingtools.
 11. The machine of claim 9, wherein each tamping tool comprisesan upper portion extending from the pivot into the housing and a lowerportion extending downwardly from the pivotal mounting and outwardly ofthe housing, the lower portion constituting a mount for a tamping tooljaw, the lower portion of the tamping tool has a forked upper endgrasping the lower end of the upper tamping tool portion, and a bolydetachably fastening the last-named ends together.